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How to do sql filtering in php

angryTom
angryTomOriginal
2019-10-19 14:15:133546browse

How to do sql filtering in php

php如何做sql过滤

SQL注入攻击指的是通过构建特殊的输入作为参数传入Web应用程序,而这些输入大都是SQL语法里的一些组合,通过执行SQL语句进而执行攻击者所要的操作,其主要原因是程序没有细致地过滤用户输入的数据,致使非法数据侵入系统。因此,在执行sql语句前,一定要对用户输入的数据进行过滤处理。

防止sql注入的函数,过滤掉那些非法的字符,提高sql安全性,同时也可以过滤XSS的攻击。

function filter($str)
{
    if (empty($str)) return false;
    $str = htmlspecialchars($str);
    $str = str_replace( '/', "", $str);
    $str = str_replace( '"', "", $str);
    $str = str_replace( '(', "", $str);
    $str = str_replace( ')', "", $str);
    $str = str_replace( 'CR', "", $str);
    $str = str_replace( 'ASCII', "", $str);
    $str = str_replace( 'ASCII 0x0d', "", $str);
    $str = str_replace( 'LF', "", $str);
    $str = str_replace( 'ASCII 0x0a', "", $str);
    $str = str_replace( ',', "", $str);
    $str = str_replace( '%', "", $str);
    $str = str_replace( ';', "", $str);
    $str = str_replace( 'eval', "", $str);
    $str = str_replace( 'open', "", $str);
    $str = str_replace( 'sysopen', "", $str);
    $str = str_replace( 'system', "", $str);
    $str = str_replace( '$', "", $str);
    $str = str_replace( "'", "", $str);
    $str = str_replace( "'", "", $str);
    $str = str_replace( 'ASCII 0x08', "", $str);
    $str = str_replace( '"', "", $str);
    $str = str_replace( '"', "", $str);
    $str = str_replace("", "", $str);
    $str = str_replace("&gt", "", $str);
    $str = str_replace("&lt", "", $str);
    $str = str_replace("<SCRIPT>", "", $str);
    $str = str_replace("</SCRIPT>", "", $str);
    $str = str_replace("<script>", "", $str);
    $str = str_replace("</script>", "", $str);
    $str = str_replace("select","",$str);
    $str = str_replace("join","",$str);
    $str = str_replace("union","",$str);
    $str = str_replace("where","",$str);
    $str = str_replace("insert","",$str);
    $str = str_replace("delete","",$str);
    $str = str_replace("update","",$str);
    $str = str_replace("like","",$str);
    $str = str_replace("drop","",$str);
    $str = str_replace("DROP","",$str);
    $str = str_replace("create","",$str);
    $str = str_replace("modify","",$str);
    $str = str_replace("rename","",$str);
    $str = str_replace("alter","",$str);
    $str = str_replace("cas","",$str);
    $str = str_replace("&","",$str);
    $str = str_replace(">","",$str);
    $str = str_replace("<","",$str);
    $str = str_replace(" ",chr(32),$str);
    $str = str_replace(" ",chr(9),$str);
    $str = str_replace("    ",chr(9),$str);
    $str = str_replace("&",chr(34),$str);
    $str = str_replace("&#39;",chr(39),$str);
    $str = str_replace("<br />",chr(13),$str);
    $str = str_replace("&#39;&#39;","&#39;",$str);
    $str = str_replace("css","&#39;",$str);
    $str = str_replace("CSS","&#39;",$str);
    $str = str_replace("<!--","",$str);
    $str = str_replace("convert","",$str);
    $str = str_replace("md5","",$str);
    $str = str_replace("passwd","",$str);
    $str = str_replace("password","",$str);
    $str = str_replace("../","",$str);
    $str = str_replace("./","",$str);
    $str = str_replace("Array","",$str);
    $str = str_replace("or 1=&#39;1&#39;","",$str);
    $str = str_replace(";set|set&set;","",$str);
    $str = str_replace("`set|set&set`","",$str);
    $str = str_replace("--","",$str);
    $str = str_replace("OR","",$str);
    $str = str_replace(&#39;"&#39;,"",$str);
    $str = str_replace("*","",$str);
    $str = str_replace("-","",$str);
    $str = str_replace("+","",$str);
    $str = str_replace("/","",$str);
    $str = str_replace("=","",$str);
    $str = str_replace("&#39;/","",$str);
    $str = str_replace("-- ","",$str);
    $str = str_replace(" -- ","",$str);
    $str = str_replace(" --","",$str);
    $str = str_replace("(","",$str);
    $str = str_replace(")","",$str);
    $str = str_replace("{","",$str);
    $str = str_replace("}","",$str);
    $str = str_replace("-1","",$str);
    $str = str_replace("1","",$str);
    $str = str_replace(".","",$str);
    $str = str_replace("response","",$str);
    $str = str_replace("write","",$str);
    $str = str_replace("|","",$str);
    $str = str_replace("`","",$str);
    $str = str_replace(";","",$str);
    $str = str_replace("etc","",$str);
    $str = str_replace("root","",$str);
    $str = str_replace("//","",$str);
    $str = str_replace("!=","",$str);
    $str = str_replace("$","",$str);
    $str = str_replace("&","",$str);
    $str = str_replace("&&","",$str);
    $str = str_replace("==","",$str);
    $str = str_replace("#","",$str);
    $str = str_replace("@","",$str);
    $str = str_replace("mailto:","",$str);
    $str = str_replace("CHAR","",$str);
    $str = str_replace("char","",$str);
    return $str;
}

更加简便的防止sql注入的方法(推荐使用这个):

 if (!get_magic_quotes_gpc()) // 判断magic_quotes_gpc是否为打开    
 {    
    $post = addslashes($name); // magic_quotes_gpc没有打开的时候把数据过滤    
 }    
  
 $name = str_replace("_", "\_", $name); // 把 &#39;_&#39;过滤掉  
    
 $name = str_replace("%", "\%", $name); // 把&#39; % &#39;过滤掉    
  
 $name = nl2br($name); // 回车转换    
  
 $name= htmlspecialchars($name); // html标记转换   
      
 return $name;

PHP防XSS 防SQL注入的代码

/**
 * 过滤参数
 * @param string $str 接受的参数
 * @return string
 */
static public function filterWords($str)
{
    $farr = array(
            "/<(\\/?)(script|i?frame|style|html|body|title|link|meta|object|\\?|\\%)([^>]*?)>/isU",
            "/(<[^>]*)on[a-zA-Z]+\s*=([^>]*>)/isU",
            "/select|insert|update|delete|\&#39;|\/\*|\*|\.\.\/|\.\/|union|into|load_file|outfile|dump/is"
    );
    $str = preg_replace($farr,&#39;&#39;,$str);
    return $str;
}
   
/**
 * 过滤接受的参数或者数组,如$_GET,$_POST
 * @param array|string $arr 接受的参数或者数组
 * @return array|string
 */
static public function filterArr($arr)
{
    if(is_array($arr)){
        foreach($arr as $k => $v){
            $arr[$k] = self::filterWords($v);
        }
    }else{
        $arr = self::filterWords($v);
    }
    return $arr;
}

在防止被注入攻击时,常会用到函数:htmlspecialchars()addslashes()trim()函数。这两个函数都是对特殊字符进行转义。
 
1)addslashes()作用及使用

addslashes()通常用于防止sql注入,它可对通过get,post和cookie传递过来的参数的单引号和双引号已经null前加“\”进行转义
如:如变量$str=$_POST["str"];的值为:bb' or 1='1。通过addslashes()函数过滤后会变为:bb\' or 1=\'1;

2)htmlspecialchars()作用及使用

htmlspecialchars()也是对字符进行转义,与addslashes()不同的是htmlspecialchars()是将特殊字符用引用实体替换。
如3f1c4e4b6b16bbbd69b2ee476dc4f83aalert('xss')2cacc6d41bbb37262a98f745aa00fbf0通过htmlspecialchars()过滤后为3f1c4e4b6b16bbbd69b2ee476dc4f83aalert('xss')

3)addslashes()与htmlspecialchars()的区别

除了两个函数的转义方式不同外,它们的使用也不同。
addslashes()通过用于防止sql语句注入,在执行sql语句前对通过get、post和cookie传递来的参数中的单引号,双引号,\ 和null进行转义。
但sql执行成功后,插入到数据库中的数据是不带有转义字符\的。这是如果插入到数据库中的是一些js脚本,当这些脚本被读取出来时还是会被执行。
这时我们可对读取出来的数据使用htmlspecialchars()进行过滤,避免执行被注入的脚本。

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